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587 Y. HUANG et al.: Closed Process of Shale Oil Recovery from Circulating Washing Water..., Kem. Ind. 65 (11-12) (2016) 587−594 Introduction Oil shale is one of the abundant energy resources in the world. Global oil shale reserves are estimated at 10 – 15 ∙ 10 18 kJ, which accounts for 35 % of the world’s total energy. 1 It has been used for energy technology purposes for hundreds of years. However, the total annual produc- tion of shale oil is currently estimated at only approximate- ly 140 ∙ 10 4 t in China, Estonia, Brazil, and Australia. That figure is significantly less than the production of petroleum and coal. A definite increase in the production of shale oil is projected in the short term and is likely to keep on increasing in the medium term and eventually after 2020, when conventional oil resources are projected to become scarce. 2 Current mature oil shale retorting processes are FLQ (Chi- na), Petrosix (Brazil), Kiviter (Estonia), ATP (Canada), and Galoter (Russia), 3–5 among others, and their basic charac- teristic parameters are shown in Table 1. The volume of the gas mixture that exits from retorts that utilize gas as a heat carrier is much larger than those that take solids as a heat carrier. Considering the cost and scale of operation, a water washing system is suited for the retorting process, which utilizes gas as heat carrier, while an oil washing sys- tem is mainly applied to the retorts that take solids as heat carrier. Although oil shale reserves are abundant in China, the oil content is generally low. For example, the oil content of oil shale in Fushun is 2 % – 13 %, with an average of 5.5 %, and belongs to lean ore. 5 The FLQ process is extensively used in China because of its strong lean ore treatment capabili- ty. However, some problems exist in the oil recovery pro- cess, and these problems have resulted in a low oil yield of 63 %, which is significantly less than that of other process- es. In the FLQ process, a large quantity of cooling water is used to condense the pyrolysis gas by direct contacting. Fi- nally, the oil and water are separated through a multistage process of settling and air floating. Gravity sedimentation and a floating pool often need large covered areas. Closed processing has been difficult to achieve and its absence has resulted in air pollution. In addition, the wastewater contains a variety of barely degradable substances, thereby increasing the difficulty of subsequent water treatment and inducing hazards to the surrounding soils and groundwa- ter. 6,7 This problem limits the further development of the FLQ process. Although oil shale has been identified as a potential source of liquid fuels because of its abundant reserves, the perfor- mance of oil shale in the world oil market has historically been economically unfavourable because oil shale is con- sidered a low-grade solid fuel that cannot compete with coal as a solid fuel. Without a low-cost technique to treat the circulating washing water, environmentally innocuous oil shale production is improbable, especially in China. Our proposed process, as discussed in this study, repre- sents an improved method for shale oil recovery through the FLQ process by hydrocyclones. The hydrocyclone is a typical centrifugal separating de- vice for heterogeneous phases and widely used in min- eral processing, 8 petrochemical, 9,10 food, 11 environmental 12 industries, among others. It has various advantages, such Closed Process of Shale Oil Recovery from Circulating Washing Water by Hydrocyclones DOI: 10.15255/KUI.2016.034 KUI-39/2016 Original scientific paper Received August 24, 2016 Accepted October 10, 2016 Y. Huang, a H. L. Wang, a* M. F. Bao, b D. S. Xing, b R. P. Zhang, b D. Zhao, c J. P. Li, a and X. Cui d a State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process, East China University of Science and Technology, Shanghai 200 237, P.R. China b Engineering Research Center, Fushun Mining Group Co., Ltd, Liaoning 113 006, P.R. China c China Huanqiu Contracting & Engineering Corporation Liaoning Branch, Liaoning 113 006, P.R. China d Shanghai Huachang Environmental Protection Co., Ltd, Shanghai 200 237, P.R. China Abstract The conventional oil recovery system in the Fushun oil shale retorting plant has a low oil recovery rate. A large quantity of fresh water is used in the system, thereby consuming a considerable amount of water and energy, as well as polluting the environment. This study aims to develop a closed process of shale oil recovery from the circulating washing water for the Fushun oil shale retorting plant. The process would increase oil yield and result in clean production. In this process, oil/water hydrocyclone groups were applied to decrease the oil content in circulating water and to simultaneously increase oil yield. The oil sludge was removed by the solid/liquid hydro- cyclone groups effectively, thereby proving the smooth operation of the devices and pipes. As a result, the oil recovery rate has increased by 5.3 %, which corresponds to 230 tonnes a month. Keywords Oil shale, hydrocyclone, oil recovery, water purification, sludge removal * Corresponding author: Hualin Wang, PhD e-mail address: [email protected]

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  • 587Y. HUANG et al.: Closed Process of Shale Oil Recovery from Circulating Washing Water..., Kem. Ind. 65 (11-12) (2016) 587−594

    IntroductionOil shale is one of the abundant energy resources in the world. Global oil shale reserves are estimated at 10 – 15 ∙ 1018 kJ, which accounts for 35 % of the world’s total energy.1 It has been used for energy technology purposes for hundreds of years. However, the total annual produc-tion of shale oil is currently estimated at only approximate-ly 140 ∙ 104 t in China, Estonia, Brazil, and Australia. That figure is significantly less than the production of petroleum and  coal.  A  definite  increase  in  the  production  of  shale oil is projected in the short term and is likely to keep on increasing in the medium term and eventually after 2020, when conventional oil resources are projected to become scarce.2

    Current mature oil shale retorting processes are FLQ (Chi-na), Petrosix (Brazil), Kiviter (Estonia), ATP (Canada), and Galoter (Russia),3–5 among others, and their basic charac-teristic parameters are shown in Table 1. The volume of the gas mixture that exits from retorts that utilize gas as a heat carrier is much larger than those that take solids as a heat carrier. Considering the cost and scale of operation, a water washing system is suited for the retorting process, which utilizes gas as heat carrier, while an oil washing sys-tem is mainly applied to the retorts that take solids as heat carrier.

    Although oil shale reserves are abundant in China, the oil content is generally low. For example, the oil content of oil shale in Fushun is 2 % – 13 %, with an average of 5.5 %, and

    belongs to lean ore.5 The FLQ process is extensively used in China because of its strong lean ore treatment capabili-ty. However, some problems exist in the oil recovery pro-cess, and these problems have resulted in a low oil yield of 63 %, which is significantly less than that of other process-es. In the FLQ process, a large quantity of cooling water is used to condense the pyrolysis gas by direct contacting. Fi-nally, the oil and water are separated through a multistage process of settling and air floating. Gravity sedimentation and a floating pool often need large covered areas. Closed processing  has  been  difficult  to  achieve  and  its  absence has resulted in air pollution. In addition, the wastewater contains a variety of barely degradable substances, thereby increasing the difficulty of subsequent water treatment and inducing hazards to the surrounding soils and groundwa-ter.6,7 This problem limits the further development of the FLQ process.

    Although oil shale has been identified as a potential source of liquid fuels because of its abundant reserves, the perfor-mance of oil shale in the world oil market has historically been economically unfavourable because oil shale is con-sidered a low-grade solid fuel that cannot compete with coal as a solid fuel. Without a low-cost technique to treat the circulating washing water, environmentally innocuous oil shale production is improbable, especially in China. Our proposed process, as discussed in this study, repre-sents an improved method for shale oil recovery through the FLQ process by hydrocyclones.

    The hydrocyclone is a typical centrifugal separating de-vice for heterogeneous phases and widely used in min-eral processing,8 petrochemical,9,10 food,11 environmental12 industries, among others. It has various advantages, such

    Closed Process of Shale Oil Recovery from Circulating Washing Water by Hydrocyclones

    DOI: 10.15255/KUI.2016.034KUI-39/2016

    Original scientific paperReceived August 24, 2016

    Accepted October 10, 2016

    Y. Huang,a H. L. Wang,a* M. F. Bao,b D. S. Xing,b R. P. Zhang,b D. Zhao,c J. P. Li,a and X. Cui da State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process, East China University of Science and Technology, Shanghai 200 237, P.R. China

    b Engineering Research Center, Fushun Mining Group Co., Ltd, Liaoning 113 006, P.R. Chinac China Huanqiu Contracting & Engineering Corporation Liaoning Branch, Liaoning 113 006, P.R. Chinad Shanghai Huachang Environmental Protection Co., Ltd, Shanghai 200 237, P.R. China

    AbstractThe conventional oil recovery system in the Fushun oil shale retorting plant has a low oil recovery rate. A large quantity of fresh water is used in the system, thereby consuming a considerable amount of water and energy, as well as polluting the environment. This study aims to develop a closed process of shale oil recovery from the circulating washing water for the Fushun oil shale retorting plant. The process would increase oil yield and result in clean production. In this process, oil/water hydrocyclone groups were applied to decrease the oil content in circulating water and to simultaneously increase oil yield. The oil sludge was removed by the solid/liquid hydro-cyclone groups effectively, thereby proving the smooth operation of the devices and pipes. As a result, the oil recovery rate has increased by 5.3 %, which corresponds to 230 tonnes a month.

    KeywordsOil shale, hydrocyclone, oil recovery, water purification, sludge removal

    * Corresponding author: Hualin Wang, PhD e-mail address: [email protected]

    https://doi.org/10.15255/KUI.2016.034http://dx.doi.org/10.15255/KUI.2015.031mailto:wanghl%40ecust.edu.cn?subject=

  • 588 Y. HUANG et al.: Closed Process of Shale Oil Recovery from Circulating Washing Water..., Kem. Ind. 65 (11-12) (2016) 587−594

    as simple structure, high separation efficiency, and low op-erating cost. The flow field in a hydrocyclone is shown in Fig. 1. A strong vortex flow composed of an outer spiral of downflow and an  inner  spiral of upflow  forms when  the fluid is injected tangentially into the hydrocyclone. For the solid/liquid hydrocyclone, the particles are accelerated by centrifugal force toward the wall and migrate downward to the underflow  following  the outer  spiral. Conversely,  the light oil droplets are swept into the inner spiral and move upward to the overflow. Thus, immiscible phases with dif-ferent densities are separated. The driving force for the separation comes from transforming the static energy of fluid  (fluid pressure)  into dynamic energy  (fluid velocity), which typically operates at a low pressure drop of less than 0.3 MPa.13–15

    This work aims to create a closed shale oil recovery sys-tem based on the current circulating water washing sys-tem, which increases the oil yield and offers a path toward cleaner production.

    Experimental systemClosed oil recovery process

    The closed process of oil recovery from circulating washing water by hydrocyclone groups is shown in Fig. 2. Oil shale granules with a size of 8 – 75 mm screened from the crude ore are heated at a temperature of 500 °C in the middle of the retort. The capacity of a single Fushun retort is only 100 tonnes per day, which is substantially less than that of other types of retorts. Thus, a combination of 20 retorts

    run simultaneously in an FLQ process, which generates a 52250 – 71250 m3 gas mixture per hour and shares one set of water washing and oil recovery system. To maximize the shale oil yield and minimize the condensable liquid in the retort gas, the pyrolysis gases that exit from the top of the retorts are washed by four-stage individual circulating

    Table 1 –Main oil shale retorting processTablica 1 – Glavne tehnologije ekstrakcije nafte iz naftnih škriljavaca

    TechnologyTehnologija

    FLQ Petrosix Kiviter ATP Galoterretort typevrsta retorte

    vertical cylindervertikalni cilindar

    vertical cylindervertikalni cilindar

    vertical cylindervertikalni cilindar

    rotating cylinderrotirajući cilindar

    rotating cylinderrotirajući cilindar

    heat carriernosač topline

    circulating gascirkulirajući plin

    circulating gascirkulirajući plin

    flue gasdimni plin

    shale ashpepeo škriljavca

    shale ashpepeo škriljavca

    feeding size ⁄ mmpromjer napajanja ⁄ mm

    8 – 75 6 – 75 25 – 125 0 – 25 0 – 25

    single retort capacity ⁄ t d−1kapacitet jedne retorte ⁄ t d−1

    100 6000 1500 6000 3000

    retort outlet tempera-ture ⁄ °Ctemperatura ispusta retorte ⁄ °C

    90 – 110 150 200 – 250 – 470 – 490

    oil recovery systemsustav dobivanja nafte

    water washingispiranje vodom

    water washingispiranje vodom

    oil washingispiranje naftom

    oil washingispiranje naftom

    heavy oil washingair cooler

    ispiranje teškom naftom

    hladnjak zrakarecovery efficiency ⁄ %iscrpak ⁄ % 6 90 80 85 – 90 85 – 90

    Fig. 1 – Vortex flow in hydrocycloneSlika 1 – Vrtložni tok u hidrociklonu

  • 589Y. HUANG et al.: Closed Process of Shale Oil Recovery from Circulating Washing Water..., Kem. Ind. 65 (11-12) (2016) 587−594

    water washing systems, after which an electron detarrer is used to capture the droplets (Fig. 3). The pyrolysis gases are delivered in the yellow pipelines.

    When the pyrolysis gases of 95 °C enter the gathering tube, most of the coarse shale ashes and heavy oil (accounting for 60 % of the total) are washed into the circulating water and then carried into the settling tank (volume of 175 m3). The lower level water in the settling tank with a large quantity of suspended oil sludge (a mixture of shale ash, bitumen, and water) is pumped into the sludge removal hydrocyclone (SR-hydrocyclone) group. As most of the oil sludge particles are  removed,  the overflow of  the SR-hy-drocyclone is sent to the oil recovery (OR-hydrocyclone) group for further oil/water separation. Thereafter, the pu-rified water  that exits  from  the overflow of OR-hydrocy-clone  is cooled down to 85 °C by a heat exchanger and returns to the top of the gathering tube.

    Some of  the fine  shale ashes pass  through  the gathering tube. Thus, a certain amount of oil sludge particles form in the circulating washing water in the retort gas cooling tow-er. A similar treatment process of washing water is applied in the second-stage oil recovery circulation, except the hot water is cooled by the returned retort gas (38 °C) in the upper section of the retort gas cooling tower. In addition, the volume of the settling tank is 65 m3, which is not large enough for the sedimentation.

    After two steps of water washing, nearly all the shale ashes and most of the heavy oil in pyrolysis gases are removed. Therefore, only liquid/liquid hydrocyclone groups are ap-plied for oil recovery in the last two-stage circulating wa-ter systems. With these four steps of water washing, more

    than 93 % of the condensable matter is washed into the circulating water. An electron detarrer is used to dry the retort gas because the gases (with a temperature of 38 °C) that exit from the top of the water cooling tower contain a large quantity of oil and water droplets. The designed op-erating parameters of the four-stage water washing devices are shown in Table 2. The retort gas is then sent to the power station, and the oil sludge is delivered to the filter press for dehydration. All the enriched oil that exits from the settling tank and OR-hydrocyclone groups is gathered for further settling dehydration.

    Fig. 3 – Images of cooling towers and electrostatic detarrer. The numbers on the top of the devices correspond to Fig. 2.

    Slika 3 – Fotografije rashladnih tornjeva i elektrostatskog precipi-tatora katrana. Brojevi na vrhu odgovaraju slici 2.

    Fig. 2 – Schematic of the closed process of oil recovery from circulating washing water(1) oil shale retort; (2) regenerative heating furnace; (3) OR-hydrocyclone groups; (4) SR-hydrocyclone groups; (5) water pump; (6) gathering tube; (7) retort gas cooling tower; (8) air cooling tower; (9) air compressor; (10) water cooling tower; (11) electrostatic detarrer; (12), (13) settling tank; (14) heat exchanger

    Slika 2 – Shema zatvorenog procesa dobivanja nafte iz vode za ispiranje(1) retorta za naftne škriljavce; (2) regeneracijska peć; (3) OR-hidrocikloni; (4)-hidrocikloni; (5) vodena pumpa; (6) sabirna cijev; (7) rashladni toranj za retortni plina; (8) zračni rashladni toranj; (9) zračni kompresor; (10) vode-ni rashladni toranj; (11) elektrostatski precipitator; (12), (13) taložni spremnik; (14) izmjenjivač topline

  • 590 Y. HUANG et al.: Closed Process of Shale Oil Recovery from Circulating Washing Water..., Kem. Ind. 65 (11-12) (2016) 587−594

    Hydrocyclone separation

    As the treatment capacity of a single hydrocyclone is lim-ited by its diameter, several or perhaps hundreds of hy-drocyclones are arranged in parallel to meet the large in-dustrial requirement. In order to achieve high separation efficiency,  it  is necessary  to  resolved how  to ensure uni-form pressure drop and flow distribution of each hydrocy-clone in the arrangement. According to Wang’s theory of flow distribution in manifolds,16–18 Chen et al.,19 and Hang et al.20,21 theoretically and experimentally studied uniform distribution in different types of hydrocyclone groups. In this work, the SR-hydrocyclones were arranged as the Z-Z type [Fig. 4(a)]. However, the OR-hydrocyclones were in-stalled in the shell like the U-U type [Fig. 4(b)]. The density of Fushun shale oil is approximately 900 kg m−3, and the kinematic viscosity is 1.03 ∙ 10−5 m2 s−1.

    Results and discussionSludge removal

    The  presence  of  bitumen  causes  fine  sludge  particles  to form aggregates easily because of their high adhesive ability. Abundant sludge particles cause equipment and pipeline jam, which may result in a serious unit outage or shutdown. Solid/liquid hydrocyclone groups are deployed after the settling tank to remove the fine oil sludge parti-cles. The size distribution of sludge particles is measured by a laser particle size analyser (Mastersize 2000, Malvern Instruments). The particle size distribution of the oil sludge at the inlet of SR-hydrocyclone groups is shown in Fig. 5. The particle size of the oil sludge in the circulating water of a gathering tube is substantially larger than that of a retort gas cooling tower, with the average particle sizes being 75 and 24 μm, respectively.

    Table 2 – Designed operating parameters of the major devices in the oil recovery systemTablica 2 – Operativni parametri glavnih uređaja u sustavu za izdvajanje nafte

    Gathering tubeSabirna cijev

    Retort gas cooling tower

    Rashladni toranj za retortni plin

    Air cooling towerZračni rashladni 

    toranj

    Water cooling towerVodeni rashladni

    toranj

    gas temperature(in/out) ⁄ °Ctemperatura plina (unutra/van) ⁄ °C 95/86 86/79 79/71 76/38

    water temperature(in/out) ⁄ °Ctemperatura vode (unutra/van) ⁄ °C 85/86 82/84 78/79 40/63

    circulating water flux ⁄ m3 h−1protok vode u cirkulaciji ⁄ m3 h−1 203 500 350 500

    head of pump ⁄ mvisina stupca fluida ⁄ m 100 70 60 70

    Δp of SR-hydrocyclone group ⁄ MPaΔp na skupini SR-hidrociklona ⁄ MPa 0.1 0.1 – –

    Δp of OR-hydrocyclone group ⁄ MPaΔp na skupini OR-hidrociklona ⁄ MPa  0.15  0.15 0.15 0.15

    Fig. 4 – Hydrocyclone groups. (a) SR-hydrocyclone group; (b) OR-hydrocyclone groups. The numbers on the de-vices correspond to those in Fig. 2.

    Slika 4 – Skupine hidrociklona: (a) SR-hidrocikloni, (b) OR-hidrocikloni. Brojevi odgovaraju slici 2.

  • 591Y. HUANG et al.: Closed Process of Shale Oil Recovery from Circulating Washing Water..., Kem. Ind. 65 (11-12) (2016) 587−594

    The oil sludge particles were removed by the solid/liquid hydrocyclone having a cylindrical diameter of 100 mm, and working at the pressure drop Δp of 0.1 MPa (between the  inlet  and  the  overflow  of  the  hydrocyclone),  which was in accordance with the research of Yang et al.22 The grade efficiencies  for SR-hydrocyclone groups are  shown in Fig. 6. Satisfactory separation efficiency for the circulat-ing washing water is achieved when the cut size d50 of the SR-hydrocyclone is approximately 20 – 25 μm.

    The gravimetric method is applied to determine the solids content in the water in accordance with the Chinese na-tional  standards GB 11901-89  and GB 511-88. After  the gravity settling tank, the oil sludge at the inlets of SR-hy-drocyclone groups of the gathering tube is approximately 416 mg l−1 (dry weight), and that in the retort gas cooling tower  is  195  mg l−1. However, through the SR-hydrocy-

    clone, the sludge dry weight is reduced to 47 and 27 mg l−1, respectively.

    Oil recovery

    A key component of the closed process is the OR-hydrocy-clone, which has a cylindrical diameter of 35 mm. To treat the large volume of circulating water, hundreds of de-oiling hydrocyclones were installed in parallel in a shell [Fig. 4(b)]. As the oil further separated from the circulating washing water,  two benefits were obtained, namely,  increased oil yield and enhanced condensation efficiency with  the  in-crease in the specific heat of water. 

    The total shale oil that condensed from the pyrolysis gas at the gathering tube and retort gas cooling tower was approx-imately 90 %. The operational states of OR-hydrocyclone groups are shown in Table 3. The hydrocyclone groups had a low pressure drop of 0.12 – 0.15 MPa, indicating low en-ergy consumption. The residence times of the settling tank in the gathering tube and retort gas cooling tower were 52 and 7 minutes, respectively. After exiting the settling tank, the water still had a lot of oil, especially the water from the retort gas cooling tower. As most of the shale oil was recovered in the gathering tube and the retort gas cooling tower, the low oil contents in the washing water of the last two-stage cooling towers rendered the recovered shale oil uneconomical for use as settling devices for oil/water separation. With the assistance of OR-hydrocyclone, the oil content in the circulating water was restricted to a low level. Moreover, the oil yield had increased.

    Fig. 5 – Particle size distribution of oil sludge: (a) at the inlet of SR-hydrocyclone for gathering tube, (b) at the inlet of SR-hydrocyclone for retort gas cooling tower

    Slika 5 – Raspodjela veličine čestica u naftnom mulju: (a) na izla-zu iz SR-hidrociklona u sabirnu cijev, (b) na izlazu iz SR-hidrociklona u radhladni toranj za retortni plin

    Fig. 6 – Grade  efficiency  of  SR-hydrocyclones:  (4-1)  grade  ef-ficiency  of  the  gathering  tube  SR-hydrocyclone;  (4-2) grade efficiency of the retort gas cooling tower SR-hy-drocyclone

    Slika 6 – Frakcijska djelotvornost SR-hidrociklona: (4-1) SR-hi-drociklon sabirne cijevi, (4-2) SR-hidrociklon rashladnog tornja retortnog plina

  • 592 Y. HUANG et al.: Closed Process of Shale Oil Recovery from Circulating Washing Water..., Kem. Ind. 65 (11-12) (2016) 587−594

    Table 3 – Operational states of OR-hydrocyclone groupsTablica 3 – Osobine radnih skupina OR-hidrociklona

    Device number

    Broj uređaja

     ∆p MPa

    Circulating water fluxProtok vode u cirkulaciji

    m3 h−1

    Oil mass fractionMaseni udjel nafte

    mg l−1

    inletulaz

    outletizlaz

    3–1 0.15 200 784 1143–2 0.15 500 3733 4453–3 0.12 350 770 1883–4 0.13 500 284 110

    In comparison with the conventional process, production had improved with the newly developed oil recovery pro-cess (Table 4). As the oil content of the raw material de-clined slightly, the monthly treatment of oil shale increased at an average of 4487 t to maintain productivity. With the application of the OR-hydrocyclone groups, the shale oil recovery rate increased by 5.3 %. The monthly increase of shale oil is 230 t with the same weight of the raw material.

    Table 4 – Comparison with conventional and new processesTablica 4 – Usporedba konvencionalnog i novog procesa

    Conventional process

    Konvencionalni proces

    New processNovi proces

    average mass fraction of oil in raw material ⁄ %prosječni maseni udjel  nafte u sirovini ⁄ %

    6.85 6.69

    monthly treatment of oil shale ⁄ tmjesečna prerada naftnog škriljavca ⁄ t

    60760 65247

    monthly shale oil production ⁄ tmjesečna proizvodnja  nafte iz škriljavca ⁄ t

    2621 2980

    oil recovery rate ⁄ %iscrpak nafte ⁄ % 62.97 68.27

    ConclusionThe closed process of oil recovery from the washing wa-ter was successively applied in an industrial retorting plant. With the application of hydrocyclones, this process pre-sents various advantages as follows:

    (1) The shale oil in the circulating water is further recovered by the oil/water hydrocyclone groups, thereby improv-ing the oil yield by 5.3 %. Given their high processing capability, hydrocyclones cover a smaller area than do settling devices. As the oil sludge is mostly removed by the SR-hydrocyclone groups, blockage of devices and pipes, which seriously affects production stability, is prevented effectively.

    (2) This process is closed such that the emission of pollut-ants in the circulating water is reduced and the condi-tion of the surrounding air is improved.

    SummaryThis paper introduces an improved process of shale oil recovery from washing water in the Fushun oil shale re-torting unit. Solid/liquid hydrocyclone groups were used to remove the oil sludge, which avoided the blockage of devices and pipes. In order to increase the oil yield, liquid/liquid hydrocyclone groups were used to recover the oil in the washing water. In addition, with the application of hydrocyclone groups, the circulating water systems were closed, thus decreasing the pollutant emissions to the air. According to the operating results, the oil yield increased 5.3 %. This new process has good prospects in oil shale retorting industries.

    ACKNOWLEDGEMENTSWe would like to express our thanks for the sponsorship of the National Science Foundation for Distinguished Young Scholars of China  (Grant No. 51125032) and Fun-damental Research Funds for the Central Universities (No. 222201313001).

    List of abbreviations and symbolsPopis kratica i simbola

    OR – oil recovery– izdvajanje nafte

    SR – sludge removal– uklanjanje mulja

    d50 – cut size of hydrocyclone, μm– veličina razdvajanja hidrociklona, μm

    ∆p – pressure drop, MPa– pad tlaka, MPa

  • 593Y. HUANG et al.: Closed Process of Shale Oil Recovery from Circulating Washing Water..., Kem. Ind. 65 (11-12) (2016) 587−594

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  • 594 Y. HUANG et al.: Closed Process of Shale Oil Recovery from Circulating Washing Water..., Kem. Ind. 65 (11-12) (2016) 587−594

    SAŽETAKIzdvajanje nafte naftnih škriljavaca hidrociklonima

    iz vode za ispiranje u cirkulacijiYuan Huang,a Hualin Wang,a* Mingfu Bao,b Dasong Xing,b

    Rongpu Zhang,b Da Zhao,c Jianping Li a i Xin Cui d

    Konvencionalni postupak za dobivanje nafte iz naftnih škriljavaca u pogonu Fushun ima nizak iscr-pak. Sustavu upotrebljava mnogo svježe vode te se troši mnogo energije, vode i onečišćuje okoliš.U radu se razvija zatvoreni sustav za dobivanje nafte iz naftnih škriljavaca s cirkuliranjem vode za ispiranje namijenjen retortnom postrojenju Fushun. U procesu su primijenjene skupine hidroci-klona za smanjenje količine nafte u vodi za ispiranje istodobno povećavajući iskorištenje. Naftni mulj uklonjen  je  skupinom hidrociklona čvrsto/tekuće  što osigurava miran  rad uređaja  i  cijevi. Iscrpak nafte povećao se za 5,3 %, odnosno 230 tona mjesečno.

    Ključne riječi Naftni škriljavac, hidrociklon, proizvodnja nafte, pročišćivanje vode, uklanjanje mulja

    Izvorni znanstveni radPrispjelo 24. kolovoza 2016.

    Prihvaćeno 10. listopada 2016.

    a State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process, East China University of Science and Technology, Shanghai 200 237, Kina

    b Engineering Research Center, Fushun Mining Group Co., Ltd, Liaoning 113 006, Kina

    c China Huanqiu Contracting & Engineering Corporation Liaoning Branch, Liaoning 113 006, Kina

    d Shanghai Huachang Environmental Protection Co., Ltd, Shanghai 200 237, Kina